Studies have shown that viral upper respiratory symptoms that last at least 7 - 10 days may be complicated by bacterial infections in 60% of affected adults. Because individual symptoms vary, physicians must rely on their clinical judgment to determine when an acute viral infection has been complicated by a bacterial infection. In general, it is assumed that an acute bacterial sinus infection occurs if the upper respiratory symptoms have persisted beyond 10 days. Bacterial sinusitis is usually accompanied by thickened nasal drainage, nasal congestion, facial pressure (especially one-sided or focused in one particular sinus area), post nasal drip, decreased sense of smell, fever, cough, fatigue, dental pain and/or ear pressure.
Most acute bacterial sinus infections in both children and adults are caused by 1 of 3 microorganisms: Streptococcus pneumoniae, Haemophilus influenzae or Moraxella catarrhalis. Other common organisms include other streptococcus species, Staphylococcus and anaerobic bacteria (bacteria that do not require an oxygen environment).